46 ORNITHOLOGICAL EXPLORATIONS 



feathers, ready to be exchauged for new ones after the incubating 

 season. 



I may, therefore, be excused for doubting the correctness of the state- 

 ment that there is a prenuptial moult of the wing-feathers in Fratercula 

 arciica, the much more so as the material of the latter, which I have 

 been able to examine, in no way corroborates the observation of Mr. 

 Bureau. That the process should be so radically different in the two 

 species of Fratercula is more than improbable. The question as to the 

 moult of the remiges of -F. arctica may yet be regarded as an open one, 

 and ornithologists, having the opportunity of making observations 

 should not omit them in the belief that all is known about the matter. 



About the moulting of the rest of the plumage in spring the previous 

 statements are conflicting. Bureau (1. c.) says that the spring moult is 

 complete, while Dr. Dybowski (Orn. Centrbl., 1882, p. 40) asserts that 

 " in spring the moult is only partial," and restricted to the outgrowth of 

 the ornamental feathers, and the moult of the wing and tail-feathers. 

 Whether the latter statement, about the wing and tail-feathers, pre- 

 tends to be based upon actual observations cannot be ascertained, and 

 may therefore be regarded as valueless in view of the remarks above. 

 As to the moult of the contour feathers, however, Mr. Bureau is un- 

 doubtedly correct, as I can testify from actual observation, only with 

 the addition that the regular time is not in spring, but in the latter part 

 of the winter. It may be remarked, though, that the individual varia- 

 tion in this respect js very great, as in so many other sea birds. 



Dr. Dybowski has of late (Bull. Soc. Zool. France, 1884, p. 348) ad- 

 vanced another erroneous theory in regard to the moult of Lunda cir- 

 rhata. He states that the young of the latter in the first plumage has the 

 under surface pure white, and that the same birds early in spring, before 

 the spring moult, are dark all over, as are the adults. He, therefore, 

 concludes that a moult must have taken place between these two phases, 

 "something similar to that which occurs in the young Tetraonidce^' (!). 

 In the first place, the young of Lunda cirrhata in the first plumage is not 

 pure white below; they are of a light gray underneath, gradually deep- 

 ening towards the chin. The shade of this gray is exceedingly variable, 

 however; in some quite light, almost whitish; in others much deeper, 

 corresponding to a similar variability of the intensity of the dark under 

 surface of the adults ; and of the four half-fledged young collected by 

 me, and partly yet in the down, no two are exactly alike, while the full- 

 grown young bird obtained iu February (No, 92922) is completely inter- 



